This invention relates to a catalytic heater. The device of the present invention was specifically designed for use in a pipe heating apparatus of the type disclosed in applicant's co-pending Canadian patent application, Ser. No. 2,004,221, filed Nov. 29, 1989. However, the heater of the present invention can be used in other situations requiring a catalytic heater.
When using flameless, gas fired, catalytic heaters, it is common practice to introduce fuel into a gas-tight housing where the fuel expands to fill the housing completely. As the fuel passes through the catalyst bed located on the front surface of the housing, ambient air mixes with the fuel permitting catalytic oxidation to occur in the catalyst bed. The catalyst bed usually consists of platinum group metals or compounds carried on a ceramic wool or ceramic board. The products of the catalytic reaction, namely carbon dioxide and water vapour pass are discharged through the front surface of the catalyst bed. Convection currents dissipate the products of reaction and re-introduce oxygen from the atmosphere to sustain the catalytic reaction.
The main limiting factor controlling the rate of catalytic reaction per unit area of catalyst bed is the rate of convection flow over the active catalytic surface. The rate of reaction is greatly reduced when the catalyst bed is horizontal, because convection circulation is substantially reduced. One solution to the problem is the use of fans to increase air flow of the catalytic surface.
The object of the present invention is to offer a more effective solution to the above defined problem by providing a relatively simple catalytic heater, in which a gas/air mixture is introduced into the heater so that a substantially large quantity of fuel mixture is uniformly delivered to the catalyst bed.
The use of the heater of the present invention permits substantial increases (as high as 33%) in heat output per unit area of catalyst bed. Moreover, the introduction of a fuel mixture into a housing under pressure dramatically reduces the problem of operating a catalytic heater upside down or face down, i.e. there appears to be no reaction in the rate of catalytic reaction when the heater is operated face down.